1. Field of the Disclosure
The present invention relates generally to apparatus for energy storage.
2. Description of the Related Art
Current energy storage techniques are either expensive, have poor charge/discharge efficiencies or have unwanted environmental consequences due to the types of chemicals involved or type of land use.
The storage techniques that are currently available that use no chemicals are: pumped hydro storage; flywheel storage; and compressed air energy storage (CAES). These techniques all have certain advantages and disadvantages:
Pumped hydro—require a certain geological set-up and has limited storage capacity. To increase storage requires a large area of land per unit of power stored.
Flywheels—good charge/discharge efficiency, but limited power storage per unit mass and expensive.
Compressed Air Energy Storage—the main drawback of CAES is its reliance on geological structures: the lack of suitable underground caverns substantially limits the usability of this storage method. However, for locations where it is suitable, it can provide a viable option for storing large quantities of energy for long periods. To store compressed air in man-made pressure vessels is problematic since large wall thicknesses are typically required. This means there are no economies of scale using manufactured pressured vessels. In addition, charge/discharge efficiency is not high.
Accordingly, there is a desire to provide an improved way of storing energy which overcomes, or at least alleviates some of the problems associated with the prior art. In particular, there is a desire to provide a cheap, efficient, relatively compact and environmentally inert alternative to current techniques.